\\[-1.8ex] Soil Heterogeneity & $-$4.560$^{***}$ & $-$4.568$^{***}$ & $-$3.713$^{***}$ & $-$2.654$^{**}$ & $-$2.132$^{***}$ & $-$2.192$^{***}$ \\ 
  & (1.343) & (1.361) & (1.053) & (1.083) & (0.807) & (0.790) \\ 
\\[-1.8ex] 
Observations & 23,437 & 23,437 & 23,437 & 23,437 & 23,437 & 23,375 \\ 
R$^{2}$ & 0.006 & 0.040 & 0.234 & 0.344 & 0.378 & 0.386 \\ 
